Well i give you 1 but thats more advanced...a replacement for the telnet system.
Heres what i thought so far, a command line client coded in java that communicates with both login and gameserver(without a network connection for security reasons), and perform tasks such as server status print, ban/kick/jail commands, maybe some donation related custom commands to give items and such, event handling, server restart/shutdown, gm follow(what actions your gm does like what admin commands he uses) and maybe with a string replacer implementation some offline functions like config editing purely in cmd.
to give you an example of a command:
l2jclient --gameserver --kickAcc --accName